Whistle



FIG. 1 is a perspective view of a whistle showing my new design;

FIG. 2 is a front (rear) view thereof;

FIG. 3 is a left (right) side view thereof;

FIG. 4 is a top plan view thereof; and,

FIG. 5 is bottom plan view thereof.

The ornamental design for a whistle, as shown and described.